What is a Predicate interface?

A Predicate is a functional interface that represents a function, which takes an Object and returns a boolean. It is used in several Stream methods like filter(), which uses Predicate to filter unwanted elements.

public boolean test(T object){
   return boolean; 
}

Predicate has test() method which takes an object and returns a boolean. The method is used to test a condition if it passes; it returns true otherwise false.

public class Java8PredicateExample {

    public static void main(String[] args) {

        List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

        List<Integer> collect = list.stream().filter(x -> x > 5).collect(Collectors.toList());

        System.out.println(collect); // [6, 7, 8, 9, 10]

    }

}

In the above example, filter method takes a predicate x -> x > 5 as argument and filters value if it is less than 5 or not.

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